Evaluation of the use of liquid metals as plasma-facing materials in fusion devices

Fission neutrons for materials testing have been available for decades in hundreds of experimental reactors worldwide; an extensive database for irradiated materials is available. Unfortunately, experimental Fusion reactors for materials testing do not exist. Testing facilities with a 14 MeV neutron source for irradiating candidate materials under Fusion-reactor conditions and offering control of the temperature of the irradiated material have been subject of development for four decades, but now have become an urgent need and crucial feature in world Fusion roadmaps. The available volumes for testing will be though reduced; in the design of IFMIF (International Fusion Materials Irradiation Facility) or its simplified versions the Japanese A-FNS or the European IFMIF/DONES, a maximum of 500 cm3 will allow the irradiation of structural materials at the needed dpa values. The optimization of the limited testing space makes indispensable the use of small specimens.The limited testing volume with needed neutron fluxes in accelerator driven Fusion relevant neutron sources drove the development of small specimens for fusion applications. The first review of the state-of-the-art dates from 1983. The development has continued in a steady manner in various laboratories worldwide yielding similar results, but without a standard procedure. Since 1983, more than 10 specific Symposia have taken place, mainly organized by ASTM, but no harmonization of small specimens test techniques has been accomplished so far.The nuclear industry, and in particular Fusion, has found that the lack of common uses in Small Specimen Test Techniques (SSTT) is preventing them to be able to compare and exchange data in an optimal manner. This would avoid duplication of experiments, need of material to be tested, etc. This CRP seeks to coordinate and encourage focused efforts in the production of guidelines for SSTT based on common agreed best practices on main test techniques (tensile, creep, low cycle fatigue, fracture toughness, fatigue crack growth rate) for reference structural Fusion materials. The final goal of this effort is a full standardization of the SSTT